This is a 371 of PCT/JP99/03706, filed on Jul. 8, 1999.
The present invention relates to a BS digital broadcasting receiver, and more particularly to a BS digital broadcasting receiver with a Reed-Solomon decoder for decoding Reed-Solomon codes.
BS digital broadcasting uses a combination of Trellis coding 8PSK (simply called Trellis 8PSK, where applicable) modulation, QPSK modulation and BPSK modulation. In BS digital broadcasting, most fundamental information on main signal transmission necessary for demodulating a transmitted signal is transmitted. For example, a transmission and multiplexing configuration control (TMCC) signal indicating a modulation method, an error correction method or the like is transmitted.
More specifically, Reed-Solomon (RS) codes are adopted for error correction of both the TMCC signal and the MPEG2-transport stream (described as TS) packet of a main signal to realize concatenation coding by using inner codes as convolutional codes and outer codes as Reed-Solomon codes.
Reed-Solomon (RS) codes used are RS (64, 48) and RS (204, 188) of a reduction type from RS (255, 239). The former is adopted for the TMCC signal and the latter is adopted for the MPEG2-TS packet of the main signal. Error correction by Reed-Solomon codes is performed once per one superframe (made of eight frames) for the TMCC signal and 48 times at a maximum per one frame for the MPEG2-TS packet of the main signal.
The BS digital broadcasting method and the structure and technical scheme of a transmission encoding unit are already known (e.g., Official Gazette, Jun. 11, 1998, Extra Edition No. 116).
In such a digital receiver, e.g., a BS digital broadcasting receiver for receiving a BS digital broadcasting program, Reed-Solomon decoding is required to be executed once per one superframe for the TMCC signal and 48 times at a maximum per one frame for the MPEG2-TS of the main signal. Furthermore, the data series of the MPEG2-TS packets of the main signal are generally continuous, whereas the TMCC signal has a data rate different from that of the MPEG2-TS packets. Therefore, error correction by Reed-Solomon codes (also described decoding by Reed-Solomon codes) is generally executed by different circuits for the MPEG2-TS packets and for the TMCC signal. It is not efficient to execute decoding of the Reed-Solomon codes and MPEG2-TS packets of the main signal by using different circuits.
It is an object of the invention to provide a digital receiver such as a BS digital broadcasting receiver, capable of decoding Reed-Solomon codes for both the TMCC signal and the MPEG2-TS packets by using a single decoder.
A digital receiver of this invention receives a data signal of a type that one frame is constituted of a plurality of slots each having a main signal added with first error correction data and a TMCC signal added with second error correction data and a superframe is constituted of a plurality of frames. The digital receiver comprises: means for separating the data signal demodulated into the main signal and the TMCC signal; means for adding the separated TMCC signal to the main signal of a last frame of the superframe; and an error correction decoder for error-correcting the main signal and the TMCC signal by decoding the data signal added with the separated TMCC signal by using predetermined error correction data as the basis of the first and second error correction data.
A BS digital broadcasting receiver of this invention receives a data signal of a type that a slot is constituted of a portion of a TMCC signal, a main signal added with error correction data basing upon a first Reed-Solomon code, and a burst symbol signal, a frame is constituted of a plurality of slots, a superframe is constituted of a plurality of frames, the TMCC signal is constituted of a collection of portions of the TMCC signal of one superframe and error correction data basing upon a second Reed-Solomon code added to the collection of portions of the TMCC signal, and the first and second Reed-Solomon codes are reductions from a same basic Reed-Solomon code. The BS digital broadcasting receiver comprises: separating means for separating the data signal demodulated into the main signal and the TMCC signal; removing means for removing the burst symbol signal when a deinterleaving circuit deinterleaves the separated main signal; adding means for adding the separated TMCC signal after the main signal of a last frame of the superframe; and a Reed-Solomon code decoder for error-correcting the main signal and the TMCC signal by decoding the main signal of a last frame of the superframe added with the separated TMCC signal by using the basic Reed-Solomon code.
In the BS digital broadcasting receiver of the invention, the separating means separates the demodulated reception data into the main signal and TMCC signal. The removing means removes the burst symbol signal when a deinterleaving circuit deinterleaves the separated main signal. The adding means adds the separated TMCC signal after the main signal of a last frame of the superframe. The Reed-Solomon code decoder error-corrects the main signal and the TMCC signal by decoding the main signal of a last frame of the superframe added with the separated TMCC signal by using the basic Reed-Solomon code. Accordingly, only one Reed-Solomon code decoder is sufficient.